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implement MA negation of a polynomial #285

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implement MA negation of a polynomial #285

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13 changes: 13 additions & 0 deletions src/operators.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -264,6 +264,19 @@ end
Base.isapprox(p::_APL, α; kwargs...) = isapprox(promote(p, α)...; kwargs...)
Base.isapprox(α, p::_APL; kwargs...) = isapprox(promote(p, α)...; kwargs...)

MA.operate!(::typeof(-), ::AbstractTermLike) = error("not implemented yet")

MA.operate_to!(::AbstractTermLike, ::typeof(-), ::_APL) = error("not implemented yet")
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Why don't we just keep the MethodError ?

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AbstractTermLike subtypes _APL, so we have to have a separate method. Do you want me to do throw(MethodError(...)) instead of error("not implemented yet")?


function MA.operate!(::typeof(-), p::_APL)
negate!! = x -> MA.operate!!(-, x)
return map_coefficients!(negate!!, p, nonzero = true)
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You can use Base.Fix1(MA.operate!!, -) to avoid creating a closure that might allocate

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You can use Base.Fix1(MA.operate!!, -)

I prefer to never use either Fix1 or Fix2, because I can never remember which is which. Should I?

to avoid creating a closure that might allocate

In this case this is not an issue, as the closure doesn't capture any variables.

end

function MA.operate_to!(o::P, ::typeof(-), p::P) where {P<:_APL}
return map_coefficients_to!(o, -, p, nonzero = true)
end

# `MA.operate(-, p)` redirects to `-p` as it assumes that `-p` can be modified
# through the MA API without modifying `p`. We should either copy the monomial
# here or implement a `MA.operate(-, p)` that copies it. We choose the first
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